The present invention relates to a racquet.
The "sweet-spot" of a racquet is that region of the head of the racquet for which impact by a ball during play imparts little or no reaction at the hand grip of the racquet, so that the player experiences little or no jarring or kicking action of the hand grip in his hand as the stroke is played.
The "sweet-spot" of a racquet may alternatively be defined as that region of the head of the racquet for which the coefficient of restitution, being the quotient of (a) the velocity of the ball relative to the racquet on rebound divided by (b) the relative approach velocity, is at its greatest, or nearly so, during play.
Hitherto, the head of a tennis racquet, for example, has been made with an oval or egg-shape, the major axis of this shape coinciding with the centre-line of the shaft of the racquet. The strings of the head extend parallel with and perpendicular to the major axis. Furthermore the sweet spot, being that area of the head of the racquet which is most effective in striking the ball, is off-centre in relation to the head. Although the sweet spot lies on the major axis, it is below the centre of the racquet head, being spaced therefrom in a direction towards the hand grip. This means that only a relatively small proportion of the racquet head is useful in striking the ball. Also, there is an asymmetry in the amount of error allowed for in different directions from the centre of the sweet spot. Thus the accuracy with which the ball must be struck in terms of the distance of the centre of impact or the centre of percussion from the centre of the sweet spot in a direction towards the hand grip is much greater than it is in relation to the distance of the centre of percussion from the centre of the sweet spot in a direction away from the hand grip. Also, there is an asymmetry in the manner in which the strings yield an impact even at the centre of the sweet spot.